Suction cups are generally comprised of a cup portion with a neck extending therefrom. The cup portion has an external convex surface and an internal concave gripping surface which is pressed against a window or other clean, smooth mounting surface for attachment thereto. When the suction cup is pressed against the mounting surface, air is forced from under the concave gripping surface. As the cup portion tries to return to its original shape, a vacuum is created which holds the suction cup against the mounting surface.
Usually suction cups are formed in a mold from a soft, pliable material such as rubber, PVC or various soft plastics having a durometer of 50 to 75. Suction cups made from these plastics work well, but have limited memory. After adhering to a mounting surface for a period of time, particularly a window exposed to light, the suction cups lose their memory and flatten out. When a suction cup has flattened out, there is little or no internal tension to hold the cup against the window. Because of this lack of memory in the perimeter of the suction cup, the perimeter of the suction cup tends to curl back. That allows air to enter the vacuum between the cup and the glass, causing the cup to release from the mounting surface. Such a loss of memory prevents reuse and the cup must be discarded.
Another conventional suction cup comprises a cup portion, a second layer which fits over the cup portion and a mechanism which when activated pulls the center of the suction cup away from the mounting surface toward the second layer in order to increase the degree of suction. The utilization of this mechanism makes this suction cup a complex and relatively expensive structure. Thus, there is a need for a suction cup which retains its memory longer and, therefore, has a longer period of use. Such a product should also be relatively inexpensive.